Fix two ubsan failures (PR85164)

Two fixes for UB when handling very large offsets.  The calculation in
force_int_to_mode would have been correct if signed integers used modulo
arithmetic, so just switch to unsigned types.  The calculation in
rtx_addr_can_trap_p_1 didn't handle overflow properly, so switch to
known_subrange_p instead (which is supposed to handle all cases).

2019-04-18  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	PR middle-end/85164
	* combine.c (force_int_to_mode): Cast the argument rather than
	the result of known_alignment.
	* rtlanal.c (rtx_addr_can_trap_p_1): Use known_subrange_p.

gcc/testsuite/
	PR middle-end/85164
	* gcc.dg/pr85164-1.c, gcc.dg/pr85164-2.c: New tests.

From-SVN: r270442

gcc/ChangeLog

+2019-04-18  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR middle-end/85164
+	* combine.c (force_int_to_mode): Cast the argument rather than
+	the result of known_alignment.
+	* rtlanal.c (rtx_addr_can_trap_p_1): Use known_subrange_p.
+
 2019-04-18  Richard Biener  <rguenther@suse.de>
 
 	PR debug/90131

gcc/combine.c

@@ -8946,7 +8946,7 @@ force_int_to_mode (rtx x, scalar_int_mode mode, scalar_int_mode xmode,
       /* If X is (minus C Y) where C's least set bit is larger than any bit
 	 in the mask, then we may replace with (neg Y).  */
       if (poly_int_rtx_p (XEXP (x, 0), &const_op0)
-	  && (unsigned HOST_WIDE_INT) known_alignment (const_op0) > mask)
+	  && known_alignment (poly_uint64 (const_op0)) > mask)
 	{
 	  x = simplify_gen_unary (NEG, xmode, XEXP (x, 1), xmode);
 	  return force_to_mode (x, mode, mask, next_select);

gcc/rtlanal.c

@@ -521,7 +521,7 @@ rtx_addr_can_trap_p_1 (const_rtx x, poly_int64 offset, poly_int64 size,
 
 	  return (!known_size_p (decl_size) || known_eq (decl_size, 0)
 		  ? maybe_ne (offset, 0)
-		  : maybe_gt (offset + size, decl_size));
+		  : !known_subrange_p (offset, size, 0, decl_size));
         }
 
       return 0;

gcc/testsuite/ChangeLog

+2019-04-18  Richard Sandiford  <richard.sandiford@arm.com>
+
+	PR middle-end/85164
+	* gcc.dg/pr85164-1.c, gcc.dg/pr85164-2.c: New tests.
+
 2019-04-18  Richard Biener  <rguenther@suse.de>
 
 	PR debug/90131

gcc/testsuite/gcc.dg/pr85164-1.c

+/* { dg-options "-O2 -w" } */
+a[];
+b;
+c() {
+  unsigned long d;
+  b = a[d - 1 >> 3];
+}

gcc/testsuite/gcc.dg/pr85164-2.c

+/* { dg-options "-O2 -w" } */
+int a;
+long b;
+void c() { b = -9223372036854775807L - 1 - a; }